How to use the pip.exceptions.InstallationError function in pip

for version_control in vcs:
        if url.lower().startswith('%s:' % version_control):
            url = '%s+%s' % (version_control, url)
            break

    if '+' not in url:
        if default_vcs:
            warnings.warn(
                "--default-vcs has been deprecated and will be removed in "
                "the future.",
                RemovedInPip10Warning,
            )
            url = default_vcs + '+' + url
        else:
            raise InstallationError(
                '%s should either be a path to a local project or a VCS url '
                'beginning with svn+, git+, hg+, or bzr+' %
                editable_req
            )

    vc_type = url.split('+', 1)[0].lower()

    if not vcs.get_backend(vc_type):
        error_message = 'For --editable=%s only ' % editable_req + \
            ', '.join([backend.name + '+URL' for backend in vcs.backends]) + \
            ' is currently supported'
        raise InstallationError(error_message)

    package_name = Link(url).egg_fragment
    if not package_name:
        raise InstallationError(

return
        assert self.req is not None
        assert self._temp_build_dir
        old_location = self._temp_build_dir
        new_build_dir = self._ideal_build_dir
        del self._ideal_build_dir
        if self.editable:
            name = self.name.lower()
        else:
            name = self.name
        new_location = os.path.join(new_build_dir, name)
        if not os.path.exists(new_build_dir):
            logger.debug('Creating directory %s' % new_build_dir)
            _make_build_dir(new_build_dir)
        if os.path.exists(new_location):
            raise InstallationError(
                'A package already exists in %s; please remove it to continue'
                % display_path(new_location))
        logger.debug('Moving package %s from %s to new location %s'
                     % (self, display_path(old_location), display_path(new_location)))
        shutil.move(old_location, new_location)
        self._temp_build_dir = new_location
        self.source_dir = new_location
        self._egg_info_path = None

def from_dist(cls, dist, dependency_links):
        location = os.path.normcase(os.path.abspath(dist.location))
        comments = []
        from pip.vcs import vcs, get_src_requirement
        if dist_is_editable(dist) and vcs.get_backend_name(location):
            editable = True
            try:
                req = get_src_requirement(dist, location)
            except InstallationError as exc:
                logger.warning(
                    "Error when trying to get requirement for VCS system %s, "
                    "falling back to uneditable format", exc
                )
                req = None
            if req is None:
                logger.warning(
                    'Could not determine repository location of %s', location
                )
                comments.append(
                    '## !! Could not determine repository location'
                )
                req = dist.as_requirement()
                editable = False
        else:
            editable = False

self.unzip_file(filename, location, flatten=not filename.endswith('.pybundle'))
        elif (content_type == 'application/x-gzip'
              or tarfile.is_tarfile(filename)
              or splitext(filename)[1].lower() in ('.tar', '.tar.gz', '.tar.bz2', '.tgz', '.tbz')):
            self.untar_file(filename, location)
        elif (content_type and content_type.startswith('text/html')
              and is_svn_page(file_contents(filename))):
            # We don't really care about this
            from pip.vcs.subversion import Subversion
            Subversion('svn+' + link.url).unpack(location)
        else:
            ## FIXME: handle?
            ## FIXME: magic signatures?
            logger.fatal('Cannot unpack file %s (downloaded from %s, content-type: %s); cannot detect archive format'
                         % (filename, location, content_type))
            raise InstallationError('Cannot determine archive format of %s' % location)

# evaluate it.
            no_marker = Requirement(str(self.req))
            no_marker.marker = None
            self.satisfied_by = pkg_resources.get_distribution(str(no_marker))
        except pkg_resources.DistributionNotFound:
            return False
        except pkg_resources.VersionConflict:
            existing_dist = pkg_resources.get_distribution(
                self.req.name
            )
            if self.use_user_site:
                if dist_in_usersite(existing_dist):
                    self.conflicts_with = existing_dist
                elif (running_under_virtualenv() and
                        dist_in_site_packages(existing_dist)):
                    raise InstallationError(
                        "Will not install to the user site because it will "
                        "lack sys.path precedence to %s in %s" %
                        (existing_dist.project_name, existing_dist.location)
                    )
            else:
                self.conflicts_with = existing_dist
        return True

package is not available until we run egg_info, so the build_location
        will return a temporary directory and store the _ideal_build_dir.

        This is only called by self.egg_info_path to fix the temporary build
        directory.
        """
        if self.source_dir is not None:
            return
        assert self.req is not None
        assert self._temp_build_dir
        assert self._ideal_build_dir
        old_location = self._temp_build_dir
        self._temp_build_dir = None
        new_location = self.build_location(self._ideal_build_dir)
        if os.path.exists(new_location):
            raise InstallationError(
                'A package already exists in %s; please remove it to continue'
                % display_path(new_location))
        logger.debug(
            'Moving package %s from %s to new location %s',
            self, display_path(old_location), display_path(new_location),
        )
        shutil.move(old_location, new_location)
        self._temp_build_dir = new_location
        self._ideal_build_dir = None
        self.source_dir = new_location
        self._egg_info_path = None

) or
                                os.path.exists(
                                    os.path.join(
                                        root, dir, 'Scripts', 'Python.exe'
                                    )
                                )):
                            dirs.remove(dir)
                        # Also don't search through tests
                        elif dir == 'test' or dir == 'tests':
                            dirs.remove(dir)
                    filenames.extend([os.path.join(root, dir)
                                     for dir in dirs])
                filenames = [f for f in filenames if f.endswith('.egg-info')]

            if not filenames:
                raise InstallationError(
                    'No files/directories in %s (from %s)' % (base, filename)
                )
            assert filenames, \
                "No files/directories in %s (from %s)" % (base, filename)

            # if we have more than one match, we pick the toplevel one.  This
            # can easily be the case if there is a dist folder which contains
            # an extracted tarball for testing purposes.
            if len(filenames) > 1:
                filenames.sort(
                    key=lambda x: x.count(os.path.sep) +
                    (os.path.altsep and x.count(os.path.altsep) or 0)
                )
            self._egg_info_path = os.path.join(base, filenames[0])
        return os.path.join(self._egg_info_path, filename)

def list(self, options, args):
        if args:
            raise InstallationError(
                'You cannot give an argument with --list')
        for path in sorted(self.paths()):
            if not os.path.exists(path):
                continue
            basename = os.path.basename(path.rstrip(os.path.sep))
            if os.path.isfile(path) and zipfile.is_zipfile(path):
                if os.path.dirname(path) not in self.paths():
                    logger.notify('Zipped egg: %s' % display_path(path))
                continue
            if (basename != 'site-packages' and basename != 'dist-packages'
                and not path.replace('\\', '/').endswith('lib/python')):
                continue
            logger.notify('In %s:' % display_path(path))
            logger.indent += 2
            zipped = []
            unzipped = []

if not existing_req:
                # Add requirement
                self.requirements[name] = install_req
                # FIXME: what about other normalizations?  E.g., _ vs. -?
                if name.lower() != name:
                    self.requirement_aliases[name.lower()] = name
                result = [install_req]
            else:
                # Assume there's no need to scan, and that we've already
                # encountered this for scanning.
                result = []
                if not install_req.constraint and existing_req.constraint:
                    if (install_req.link and not (existing_req.link and
                       install_req.link.path == existing_req.link.path)):
                        self.reqs_to_cleanup.append(install_req)
                        raise InstallationError(
                            "Could not satisfy constraints for '%s': "
                            "installation from path or url cannot be "
                            "constrained to a version" % name)
                    # If we're now installing a constraint, mark the existing
                    # object for real installation.
                    existing_req.constraint = False
                    existing_req.extras = tuple(
                        sorted(set(existing_req.extras).union(
                               set(install_req.extras))))
                    logger.debug("Setting %s extras to: %s",
                                 existing_req, existing_req.extras)
                    # And now we need to scan this.
                    result = [existing_req]
                # Canonicalise to the already-added object for the backref
                # check below.
                install_req = existing_req

)
            options.ignore_installed = True

        if options.build_dir:
            options.build_dir = os.path.abspath(options.build_dir)

        options.src_dir = os.path.abspath(options.src_dir)
        install_options = options.install_options or []
        if options.use_user_site:
            if options.prefix_path:
                raise CommandError(
                    "Can not combine '--user' and '--prefix' as they imply "
                    "different installation locations"
                )
            if virtualenv_no_global():
                raise InstallationError(
                    "Can not perform a '--user' install. User site-packages "
                    "are not visible in this virtualenv."
                )
            install_options.append('--user')
            install_options.append('--prefix=')

        temp_target_dir = None
        if options.target_dir:
            options.ignore_installed = True
            temp_target_dir = tempfile.mkdtemp()
            options.target_dir = os.path.abspath(options.target_dir)
            if (os.path.exists(options.target_dir) and not
                    os.path.isdir(options.target_dir)):
                raise CommandError(
                    "Target path exists but is not a directory, will not "
                    "continue."