How to use the segyio.spec function in segyio

def mklines(fname):
    spec = segyio.spec()
    spec.format  = 5
    spec.sorting = 2
    spec.samples = 10
    spec.ilines  = range(1, 11)
    spec.xlines  = range(1, 6)

    # create a file with 10 inlines, with values on the form l.0tv where
    # l = line no
    # t = trace number (within line)
    # v = trace value
    # i.e. 2.043 is the value at inline 2's fourth trace's third value
    with segyio.create(fname, spec) as dst:
        ln = np.arange(start = 0,
                       stop = 0.001 * (5 * 10),
                       step = 0.001,
                       dtype = np.single).reshape(5, 10)

def test_create_from_naught_prestack(self):
        fname = "test-data/mk-ps.sgy"
        spec = segyio.spec()
        spec.format  = 5
        spec.sorting = 2
        spec.samples = 7
        spec.ilines  = range(1, 4)
        spec.xlines  = range(1, 3)
        spec.offsets = range(1, 6)

        cube_size = len(spec.ilines) * len(spec.xlines)

        with segyio.create(fname, spec) as dst:
            arr = np.arange( start = 0.000,
                             stop = 0.007,
                             step = 0.001,
                             dtype = np.single)

            arr = np.concatenate([[arr + 0.01], [arr + 0.02]], axis = 0)

def main():
    if len(sys.argv) < 9:
        sys.exit(" ".join(["Usage: {} [file] [samples]",
                           "[first iline] [last iline]",
                           "[first xline] [last xline]",
                           "[first offset] [last offset]"]
                         ).format(sys.argv[0]))

    spec = segyio.spec()
    filename = sys.argv[1]

    # to create a file from nothing, we need to tell segyio about the structure of
    # the file, i.e. its inline numbers, crossline numbers, etc. You can also add
    # more structural information, This is the absolute minimal specification for a
    # N-by-M volume with K offsets volume
    spec.sorting = 2
    spec.format = 1
    spec.samples = range(int(sys.argv[2]))
    spec.ilines = range(*map(int, sys.argv[3:5]))
    spec.xlines = range(*map(int, sys.argv[5:7]))
    spec.offsets = range(*map(int, sys.argv[7:9]))
    if len(spec.offsets) == 0: spec.offsets = [1]

    with segyio.create(filename, spec) as f:
        # one inline consists of 50 traces

def main():
    if len(sys.argv) < 7:
        sys.exit("Usage: {} [file] [samples] [first iline] [last iline] [first xline] [last xline]".format(sys.argv[0]))

    spec = segyio.spec()
    filename = sys.argv[1]

    # to create a file from nothing, we need to tell segyio about the structure of
    # the file, i.e. its inline numbers, crossline numbers, etc. You can also add
    # more structural information, but offsets etc. have sensible defautls. This is
    # the absolute minimal specification for a N-by-M volume
    spec.sorting = 2
    spec.format = 1
    spec.samples = range(int(sys.argv[2]))
    spec.ilines = range(*map(int, sys.argv[3:5]))
    spec.xlines = range(*map(int, sys.argv[5:7]))

    with segyio.create(filename, spec) as f:
        # one inline consists of 50 traces
        # which in turn consists of 2000 samples
        start = 0.0

def main():
    if len(sys.argv) < 3:
        sys.exit("Usage: {} [source-file] [destination-file]".format(sys.argv[0]))

    sourcefile = sys.argv[1]
    destfile = sys.argv[2]

    with segyio.open(sourcefile) as src:
        spec = segyio.spec()
        spec.sorting = int(src.sorting)
        spec.format  = int(src.format)
        spec.samples = range(50)
        spec.ilines = src.ilines[:5]
        spec.xlines = src.xlines[:5]

        with segyio.create(destfile, spec) as dst:
            # Copy all textual headers, including possible extended
            for i in range(1 + src.ext_headers):
                dst.text[i] = src.text[i]

            # copy the binary header, then insert the modifications needed for
            # the new shape
            dst.bin = src.bin
            dst.bin = { segyio.BinField.Samples: 50,
                        segyio.BinField.Traces: 5 * 5

else:
                logger.info("iline sorting")
                ixv, jyv, kzv = cvalues.shape
                for ill, iline in enumerate(segyfile.ilines):
                    if ixv != jyv != kzv or ixv != kzv != jyv:
                        segyfile.iline[iline] = cvalues[ill]  # broadcasting
                    else:
                        # safer but a bit slower than broadcasting
                        segyfile.iline[iline] = cvalues[ill, :, :]

    else:
        # NOT FINISHED!
        logger.debug("Input segy file from scratch ...")

        # sintv = int(self.zinc * 1000)
        spec = segyio.spec()

        spec.sorting = 2
        spec.format = 1

        spec.samples = np.arange(self.nlay)
        spec.ilines = np.arange(self.ncol)
        spec.xlines = np.arange(self.nrow)

        with segyio.create(sfile, spec) as fseg:

            # write the line itself to the file and the inline number
            # in all this line's headers
            for ill, ilno in enumerate(spec.ilines):
                fseg.iline[ilno] = cvalues[ill]
                # f.header.iline[ilno] = {

Returns
    -------
    spec : segyio.spec

    Notes
    -----

    .. versionadded:: 1.4

    """

    if not isinstance(f, segyio.SegyFile):
        with segyio.open(f) as fl:
            return metadata(fl)

    spec = segyio.spec()

    spec.iline = f._il
    spec.xline = f._xl
    spec.samples = f.samples
    spec.format = f.format

    spec.ilines = f.ilines
    spec.xlines = f.xlines
    spec.offsets = f.offsets
    spec.sorting = f.sorting

    spec.tracecount = f.tracecount

    spec.ext_headers = f.ext_headers
    spec.endian = f.endian