How to use the pyflakes.messages.UnusedVariable function in pyflakes

def checkUnusedAssignments():
                """
                Check to see if any assignments have not been used.
                """
                for name, binding in self.scope.unusedAssignments():
                    self.report(messages.UnusedVariable, binding.source, name)
            self.deferAssignment(checkUnusedAssignments)

def checkUnusedAssignments():
                """
                Check to see if any assignments have not been used.
                """
                for name, binding in self.scope.unusedAssignments():
                    self.report(messages.UnusedVariable, binding.source, name)
            self.deferAssignment(checkUnusedAssignments)

def checkUnusedAssignments():
                """
                Check to see if any assignments have not been used.
                """
                for name, binding in self.scope.unusedAssignments():
                    self.report(messages.UnusedVariable, binding.source, name)
            self.deferAssignment(checkUnusedAssignments)

# See discussion on https://github.com/PyCQA/pyflakes/pull/59

        # We're removing the local name since it's being unbound after leaving
        # the except: block and it's always unbound if the except: block is
        # never entered. This will cause an "undefined name" error raised if
        # the checked code tries to use the name afterwards.
        #
        # Unless it's been removed already. Then do nothing.

        try:
            binding = self.scope.pop(node.name)
        except KeyError:
            pass
        else:
            if not binding.used:
                self.report(messages.UnusedVariable, node, node.name)

        # Restore.
        if prev_definition:
            self.scope[node.name] = prev_definition

def checkUnusedAssignments():
                """
                Check to see if any assignments have not been used.
                """
                for name, binding in self.scope.unusedAssignments():
                    self.report(messages.UnusedVariable, binding.source, name)
            self.deferAssignment(checkUnusedAssignments)

def checkUnusedAssignments():
                """
                Check to see if any assignments have not been used.
                """
                for name, binding in self.scope.iteritems():
                    if (not binding.used and not name in self.scope.globals
                        and isinstance(binding, Assignment)):
                        self.report(messages.UnusedVariable,
                                    binding.source, name)
            self.deferAssignment(checkUnusedAssignments)

# See discussion on https://github.com/PyCQA/pyflakes/pull/59

        # We're removing the local name since it's being unbound after leaving
        # the except: block and it's always unbound if the except: block is
        # never entered. This will cause an "undefined name" error raised if
        # the checked code tries to use the name afterwards.
        #
        # Unless it's been removed already. Then do nothing.

        try:
            binding = self.scope.pop(node.name)
        except KeyError:
            pass
        else:
            if not binding.used:
                self.report(messages.UnusedVariable, node, node.name)

        # Restore.
        if prev_definition:
            scope, binding = prev_definition
            scope[node.name] = binding

# See discussion on https://github.com/PyCQA/pyflakes/pull/59

        # We're removing the local name since it's being unbound after leaving
        # the except: block and it's always unbound if the except: block is
        # never entered. This will cause an "undefined name" error raised if
        # the checked code tries to use the name afterwards.
        #
        # Unless it's been removed already. Then do nothing.

        try:
            binding = self.scope.pop(node.name)
        except KeyError:
            pass
        else:
            if not binding.used:
                self.report(messages.UnusedVariable, node, node.name)

        # Restore.
        if prev_definition:
            scope, binding = prev_definition
            scope[node.name] = binding

def checkUnusedAssignments():
                """
                Check to see if any assignments have not been used.
                """
                for name, binding in self.scope.iteritems():
                    if (not binding.used and not name in self.scope.globals
                        and not self.scope.usesLocals
                        and isinstance(binding, Assignment)):
                        self.report(messages.UnusedVariable,
                                    binding.source, name)
            self.deferAssignment(checkUnusedAssignments)

def unused_variable_line_numbers(messages):
    """Yield line numbers of unused variables."""
    for message in messages:
        if isinstance(message, pyflakes.messages.UnusedVariable):
            yield message.lineno