anchor.diff:  %% Function calls
   funcall -> funcall_expr '.' function_identifier '(' ')' : {funcall, line('$2'), '$1', '$3', []}.
   funcall -> funcall_expr '.' function_identifier '(' exprs ')' : {funcall, line('$2'), '$1', '$3', '$5'}.
  +funcall -> funcall_expr '[' expr ']' : {funcall, line('$2'), '$1', {identifier, line('$2'), '[]'}, ['$3']}.
  +
   funcall -> function_identifier '(' ')' : {funcall, line('$2'), '$1', []}.
   funcall -> function_identifier '(' exprs ')' : {funcall, line('$2'), '$1', '$3'}.
   
  
positive.code:   block
    inline_block
    multiline_block
    unary_expr
    unary_op  
    erl_funcall_expr
    erl_funcall
    max_expr
    ivar
    case_expr
  
negative.code: unary_expr -> funcall_expr : '$1'.
  
  funcall_expr -> funcall : '$1'.
  funcall_expr -> class_inst_expr : '$1'.
  
  class_inst_expr -> class_inst : '$1'.
  class_inst_expr -> erl_funcall_expr : '$1'.
  
  erl_funcall_expr -> erl_funcall : '$1'.
  erl_funcall_expr -> max_expr : '$1'.
  