Can you change an element of a sequence? What if a sequence is a dictionary? What if a sequence is a tuple?

Yes, we can change any element of a sequence in python only if the type of the sequence is mutable.

1. Dictionary — We can change the elements of a dictionary as dictionary is a mutable sequence. For example:
   d = {'k1':1, 'k2':4}
   d['k1'] = 2
   Here, we are changing the value of first key-value pair of dictionary d. Now dictionary d will be : {'k1':2, 'k2':4}
2. Tuple — We cannot change the elements of a tuple as tuple is an immutable sequence.
   For example:
   tup = (1, 2, 3, 4)
   tup[0] = 5
   The above expression will give an error.
   TypeError: 'tuple' object does not support item assignment