@classmethod<EOL><INDENT>def fromvalue(cls, v):<DEDENT>
if isinstance(v, text_type):<EOL><INDENT>return cls(base=v)<EOL><DEDENT>if isinstance(v, dict):<EOL><INDENT>return cls(**DescriptionBase.partition_properties(v))<EOL><DEDENT>if isinstance(v, cls):<EOL><INDENT>return v<EOL><DEDENT>raise ValueError(v)<EOL>
:param v: Initialization data for `cls`; either a single string that is the main datatype \
of the values of the cell or a datatype description object, i.e. a `dict` or a `cls`
instance.
:return: An instance of `cls`