Built-in objects like as types and functions can also be used. There are, however, a few limitations that dictionary keys must adhere to.
For starters, a key can only appear once in a dictionary. There are no duplicate keys allowed. Because a dictionary maps each key to its matching value, it's pointless to map the same key many times. If you supply a key a second time during the dictionary's initial generation, the second occurrence will take precedence over the first. cheap custom essay writing services.