def SimpleSymbols(s):
  for i in xrange(len(s)):
    if i > 0:
        # If we aren't at the first position, there are valid positions before us
        prev_c = s[i - 1]
    else:
        prev_c = None

    curr_c = s[i]

    if i < len(s) - 1:
        # If we aren't at the last position, there are valid positions after us
        next_c = s[i + 1]
    else:
        next_c = None

    # Now what?