def field_get_subfields(field):
pairs = {}<EOL>for key, value in field[<NUM_LIT:0>]:<EOL><INDENT>if key in pairs and pairs[key] != value:<EOL><INDENT>pairs[key].append(value)<EOL><DEDENT>else:<EOL><INDENT>pairs[key] = [value]<EOL><DEDENT><DEDENT>return pairs<EOL>
Given a field, will place all subfields into a dictionary
    Parameters:
     * field - tuple: The field to get subfields for
    Returns: a dictionary, codes as keys and a list of values as the value