code: def t_OPEN_TAG(t):
      r'<[?%]((php[ \t\r\n]?)|=)?'
      if '=' in t.value: t.type = 'OPEN_TAG_WITH_ECHO'
      t.lexer.lineno += t.value.count("\n")
      t.lexer.begin('php')
      return f t_OPEN_TAG(t):
      r'<[?%]((php[ \t\r\n]?)|=)?'
      if '=' in t.value: t.type = 'OPEN_TAG_WITH_ECHO'
      t.lexer.lineno += t.value.count("\n")
      t.lexer.begin('php')
      return t
docs: r'<[?%]((php[ \t\r\n]?)|=)?