@hep.over('<STR_LIT>', '<STR_LIT>')<EOL>def number_of_pages(self, key, value):
result = maybe_int(force_single_element(value.get('<STR_LIT:a>', '<STR_LIT>')))<EOL>if result and result > <NUM_LIT:0>:<EOL><INDENT>return result<EOL><DEDENT>
Populate the ``number_of_pages`` key.