rmmf
              Remove a membership function from an existing FIS structure and return the updated FIS.
The types/values of the arguments are expected to be:
| Argument | Expected Type or Value | 
|---|---|
| fis | an FIS structure | 
| in_or_out | ’input’ or ’output’ (case-insensitive) | 
| var_index | valid index of an FIS input/output variable | 
| mf | the string ’mf’ | 
| mf_index | an integer | 
Note that rmmf will allow the user to delete membership functions that are currently in use by rules in the FIS.