<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def repmct(instr, marker, value, repcase, lenout=None):
 """ Replace a marker with the text representation of a cardinal number. http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/repmc_c.html :param instr: Input string. :type instr: str :param marker: Marker to be replaced. :type marker: str :param value: Replacement value. :type value: int :param repcase: Case of replacement text. :type repcase: str :param lenout: Optional available space in output string :type lenout: int :return: Output string. :rtype: str """

    if lenout is None:
        lenout = ctypes.c_int(len(instr) + len(marker) + 15)
    instr = stypes.stringToCharP(instr)
    marker = stypes.stringToCharP(marker)
    value = ctypes.c_int(value)
    repcase = ctypes.c_char(repcase.encode(encoding='UTF-8'))
    out = stypes.stringToCharP(lenout)
    libspice.repmct_c(instr, marker, value, repcase, lenout, out)
    return stypes.toPythonString(out)