<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def choose_coord_units(header):
 """Return the appropriate key code for the units value for the axes by examining the FITS header. """

    cunit = header['CUNIT1']
    match = re.match(r'^deg\s*$', cunit)
    if match:
        return 'degree'

    # raise WCSError("Don't understand units '%s'" % (cunit))
    return 'degree'