def first_available(self, *quantities):
for i, q in enumerate(quantities):<EOL><INDENT>if self.has_quantity(q):<EOL><INDENT>if i:<EOL><INDENT>warnings.warn('<STR_LIT>'.format(quantities[<NUM_LIT:0>], q))<EOL><DEDENT>return q<EOL><DEDENT><DEDENT>
Return the first available quantity in the input arguments.
Return `None` if none of them is available.