code: def t_bin_NUMBER(t):
      r'[01]+'  # A binary integer
      t.value = int(t.value, 2)
      t.lexer.begin('INITIAL')
  
      return f t_bin_NUMBER(t):
      r'[01]+'  # A binary integer
      t.value = int(t.value, 2)
      t.lexer.begin('INITIAL')
  
      return t
docs: r'[01]+