str = 'the little dinosaur'
# format: string_name[start_pos_incl:stop_pos_excl]
# zero-based index
# the little...
# 0123456789...
print str[4:]
# >>> little dinosaur
print str[4:10]
# >>> little
# negative index: 
# count from the end of str, with -1 being the last position
print str[:-4]
# >>> the little dino
print str[-4:]
# >>> saur