def err(msg, level=-<NUM_LIT:1>, prefix=True):
if will_print(level) or verbosity is None:<EOL><INDENT>printer(("<STR_LIT>" if prefix else "<STR_LIT>") + msg, "<STR_LIT>")<EOL><DEDENT>
Prints the specified message as an error; prepends "ERROR" to
    the message, so that can be left off.