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