================================================================================
Simple var declaration
================================================================================
foo := bar
--------------------------------------------------------------------------------

(source_file
  (simple_statement
    (var_declaration
      (expression_list
        (reference_expression
          (identifier)))
      (expression_list
        (reference_expression
          (identifier))))))

================================================================================
Several var declarations
================================================================================
foo, goo := bar, zoo
--------------------------------------------------------------------------------

(source_file
  (simple_statement
    (var_declaration
      (expression_list
        (reference_expression
          (identifier))
        (reference_expression
          (identifier)))
      (expression_list
        (reference_expression
          (identifier))
        (reference_expression
          (identifier))))))
