'Create a LabelArray from a pandas categorical.
Parameters
categorical : pd.Categorical
The categorical object to convert.
missing_value : bytes, unicode, or None, optional
The missing value to use for this LabelArray.
Returns
la : LabelArray
The LabelArray representation of this categorical.'

@classmethod
def from_categorical(cls, categorical, missing_value=None):

    return LabelArray(categorical, missing_value, categorical.categories)
