code: def _unescape(s, uri=False):
      
      out = ''
      while len(s) > 0:
          c = s[0]
          if c == '\\':
              # Backslash escape
              esc_c = s[1]
  
              if esc_c in ('u', 'U'):
                  # Unicode escape
                  out += six.unichr(int(s[2:6], base=16))
                  s = s[6:]
                  continue
              else:
                  if esc_c == 'b':
                      out += '\b'
                  elif esc_c == 'f':
                      out += '\f'
                  elif esc_c == 'n':
                      out += '\n'
                  elif esc_c == 'r':
                      out += '\r'
                  elif esc_c == 't':
                      out += '\t'
                  else:
                      if uri and (esc_c == '#'):
                          # \# is passed through with backslash.
                          out += '\\'
                      # Pass through
                      out += esc_c
                  s = s[2:]
                  continue
          else:
              out += c
              s = s[1:]
      return out
docs: Iterative parser for string escapes.