def usage_function(parser):
parser.print_usage()<EOL>print('<STR_LIT>')<EOL>print('<STR_LIT>')<EOL>for function in sorted(FUNCTION):<EOL><INDENT>doc = FUNCTION[function].__doc__.strip().splitlines()[<NUM_LIT:0>]<EOL>print('<STR_LIT>' % (function + '<STR_LIT::>', doc))<EOL><DEDENT>return <NUM_LIT:0><EOL>
Show usage and available curve functions.