#! /usr/bin/python3
#

def isPhoneNumber (text):
   if len (text) != 12:
     return False

   for i in range (0, 3):
     if not text [i].isdecimal ():
        return False

   if text [3] != '-':
      return False

   for i in range (4, 7):
      if not text [i].isdecimal ():
         return False

   if text [7] != '-':
      return False

   for i in range (8, 12):
      if not text [i].isdecimal ():
         return False

   return True

print ('415-555-4242 is a phone number:')
print (isPhoneNumber ('415-555-4242'))
print ('Moshi moshi is a phone number:')
print (isPhoneNumber ('Moshi moshi'))

message = 'Call me at 415-555-1011 tomorrow. 415-555-9999 is my office.'

print ()
for i in range (len (message)):
   chunk = message [i:i+12]

   if isPhoneNumber (chunk):
      print ('Phone number found: ' + chunk)

print ('Done')
