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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def AVP(avpId, **fields):
 """ Craft an AVP based on its id and optional parameter fields"""

    val = None
    classType = AVP_Unknown
    if isinstance(avpId, str):
        try:
            for vnd in AvpDefDict:
                for code in AvpDefDict[vnd]:
                    val = AvpDefDict[vnd][code]
                    if val[0][:len(
                            avpId)] == avpId:  # A prefix of the full name is considered valid  # noqa: E501
                        raise
            found = False
        except BaseException:
            found = True
    else:
        if isinstance(avpId, list):
            code = avpId[0]
            vnd = avpId[1]
        else:  # Assume this is an int
            code = avpId
            vnd = 0
        try:
            val = AvpDefDict[vnd][code]
            found = True
        except BaseException:
            found = False
    if not found:
        warning('The AVP identifier %s has not been found.' % str(avpId))
        if isinstance(avpId, str):  # The string input is not valid
            return None
    # At this point code, vnd are provisionned val may be set (if found is True)  # noqa: E501
    # Set/override AVP code
    fields['avpCode'] = code
    # Set vendor if not already defined and relevant
    if 'avpVnd' not in fields and vnd:
        fields['avpVnd'] = vnd
    # Set flags if not already defined and possible ...
    if 'avpFlags' not in fields:
        if val:
            fields['avpFlags'] = val[2]
        else:
            fields['avpFlags'] = vnd and 128 or 0
    # Finally, set the name and class if possible
    if val:
        classType = val[1]
    _ret = classType(**fields)
    if val:
        _ret.name = 'AVP ' + val[0]
    return _ret