Handle options.

def handle_options():
    '''Handle options.
    '''
    parser = OptionParser()
    parser.set_defaults(cmaglin=False)
    parser.set_defaults(single=False)
    parser.set_defaults(alpha_cov=False)
    parser.add_option('-x',
                      '--xmin',
                      dest='xmin',
                      help='Minium X range',
                      type='float',
                      )
    parser.add_option('-X',
                      '--xmax',
                      dest='xmax',
                      help='Maximum X range',
                      type='float',
                      )
    parser.add_option('-z',
                      '--zmin',
                      dest='zmin',
                      help='Minium Z range',
                      type='float',
                      )
    parser.add_option('-Z',
                      '--zmax',
                      dest='zmax',
                      help='Maximum Z range',
                      type='float',
                      )
    parser.add_option('-c',
                      '--column',
                      dest='column',
                      help='column to plot of input file',
                      type='int',
                      default=2,
                      )
    parser.add_option('-u',
                      '--unit',
                      dest='xunit',
                      help='Unit of length scale, typically meters (m) ' +
                      'or centimeters (cm)',
                      metavar='UNIT',
                      type='str',
                      default='m',
                      )
    parser.add_option("--alpha_cov",
                      action="store_true",
                      dest="alpha_cov",
                      help="use coverage for transparency",
                      )
    parser.add_option('--cbtiks',
                      dest='cbtiks',
                      help="Number of CB tiks",
                      type=int,
                      metavar="INT",
                      default=3,
                      )
    parser.add_option("--cmaglin",
                      action="store_true",
                      dest="cmaglin",
                      help="linear colorbar for magnitude",
                      )
    parser.add_option('--mag_vmin',
                      dest='mag_vmin',
                      help='Minium of colorbar',
                      type='float',
                      )
    parser.add_option('--mag_vmax',
                      dest='mag_vmax',
                      help='Maximum of colorbar',
                      type='float',
                      )
    parser.add_option('--pha_vmin',
                      dest='pha_vmin',
                      help='Minium of colorbar',
                      type='float',
                      )
    parser.add_option('--pha_vmax',
                      dest='pha_vmax',
                      help='Maximum of colorbar',
                      type='float',
                      )
    parser.add_option('--real_vmin',
                      dest='real_vmin',
                      help='Minium of colorbar',
                      type='float',
                      )
    parser.add_option('--real_vmax',
                      dest='real_vmax',
                      help='Maximum of colorbar',
                      type='float',
                      )
    parser.add_option('--imag_vmin',
                      dest='imag_vmin',
                      help='Minium of colorbar',
                      type='float',
                      )
    parser.add_option('--imag_vmax',
                      dest='imag_vmax',
                      help='Maximum of colorbar',
                      type='float',
                      )

    (options, args) = parser.parse_args()
    return options