'Coefficient names generated based on the model\'s polynomial degree
and number of dimensions.
Subclasses should implement this to return parameter names in the
desired format.
On most `Model` classes this is a class attribute, but for polynomial
models it is an instance attribute since each polynomial model instance
can have different parameters depending on the degree of the polynomial
and the number of dimensions, for example.'

@property
def param_names(self):

    return self._param_names
