.. efun:: int test_bit(string str, int n)

  Return 0 or 1 if bit :arg:`n` was set in string :arg:`str`.

  Each character contains 6 bits. So you can store a value between 0 and 63 in one character (2^6=64). Starting character is the blank :char:`SPACE` which has the value 0. The first character in the string is the one with the lowest bits (0-5).

  .. usage::

    The below returns 1 because "_" stands for the number 63 and therefore the 6th bit is set::

      test_bit("_",5);

    The next example returns 0 because :char:`SPACE` stands for 0 and no bit is set::

      test_bit(" ",3);

  .. seealso:: :efun:`set_bit`, :efun:`clear_bit`, :efun:`last_bit`, :efun:`next_bit`, :efun:`count_bits`, :efun:`and_bits`, :efun:`or_bits`, :efun:`xor_bits`, :efun:`invert_bits`, :efun:`copy_bits`