def check_extensions(extensions: Set[str], allow_multifile: bool = False):
check_var(extensions, var_types=set, var_name='<STR_LIT>')<EOL>for ext in extensions:<EOL><INDENT>check_extension(ext, allow_multifile=allow_multifile)<EOL><DEDENT>
Utility method to check that all extensions in the provided set are valid

:param extensions:
:param allow_multifile:
:return: