Routes a category axis' value (i.e. the index) to the actual ac.ValueSet value.
Constructs a new ac.CategoryDataTypeFormatter using the given formatter.
Parameters
* values (ac.ValueSet)
* column (integer)
* formatter (ac.DataTypeFormatter)
Formats the given value. For category axes, the value has to be
of type ac.FloatDataType and is converted to an integer
since a value is always equal to the index of the value in the
ac.ValueSet.
Parameters
* value (ac.DataType or children classes)
Returns
* text value