#------------------------------------------------------------------------------
#  FindInString.py
#------------------------------------------------------------------------------

def find(s, ch):
   """
   Find and return the index of ch in string s.
   Return None if ch does not occur in string s.
   """
   i = 0
   while i < len(s):
      if s[i] == ch:
         return i
      # end if
      i += 1
   # end while
   # if execution reaches here, returns None
# end find()


#-- main program --------------------------------------------------------------

t = 'Hello, World!'
print( find(t, 'W') )
print( find(t, 'q') )