@classmethod<EOL><INDENT>def coerce(cls, key, value):<DEDENT>
if not isinstance(value, MutableList):<EOL><INDENT>if isinstance(value, list):<EOL><INDENT>return MutableList(value)<EOL><DEDENT>elif value is None:<EOL><INDENT>return value<EOL><DEDENT>else:<EOL><INDENT>return MutableList([value])<EOL><DEDENT><DEDENT>else:<EOL><INDENT>return value<EOL><DEDENT>
Convert plain list to MutableList