How to get rid of the following multiple alternatives warnings in my ANTLR3 grammar?
[11:45:19] warning(200): mygrammar.g:14:57: Decision can match input such as "','" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input
[11:45:19] warning(200): C:UsersJarrod Robersonmygrammar.g:14:57: Decision can match input such as "','" using multiple alternatives: 1, 2
As a result, alternative(s) 2 were disabled for that input

myfunction(x) ->
  sqr(a) -> a * a,
  y -> sqr(x).

function : ID '(' args ')' '->' statement (',' statement)* ;

statement : ATOM
          | expression
          | assignment
          | function
          ;

program : (statement'.')*;

f(x)-> g(y)-> y*y, x=y

function
  :  ID '(' args ')' '->' statement ((',' statement)=> ',' statement)*
  ;

myfunction(x) ->
  sqr(a) -> a * a,
  y = sqr(x).

function
  :  ID '(' args ')' '->' statement (',' statement)* '.'
  ;