def _get_f90_modules(source):
if not f90_ext_match(source):<EOL><INDENT>return []<EOL><DEDENT>modules = []<EOL>f = open(source, '<STR_LIT:r>')<EOL>for line in f:<EOL><INDENT>m = f90_module_name_match(line)<EOL>if m:<EOL><INDENT>name = m.group('<STR_LIT:name>')<EOL>modules.append(name)<EOL><DEDENT><DEDENT>f.close()<EOL>return modules<EOL>
Return a list of Fortran f90 module names that
    given source file defines.