Write a function to drop empty items from a given dictionary.
def drop_empty(dict1):
  dict1 = {key:value for (key, value) in dict1.items() if value is not None}
  return dict1
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to drop empty items from a given dictionary.
def drop_empty(dict1):
  dict1 = {key:value for (key, value) in dict1.items() if value is not None}
  return dict1[/INST]assert drop_empty({'c1': 'Red', 'c2': 'Green', 'c3':None})=={'c1': 'Red', 'c2': 'Green'}
assert drop_empty({'c1': 'Red', 'c2': None, 'c3':None})=={'c1': 'Red'}
assert drop_empty({'c1': None, 'c2': 'Green', 'c3':None})=={ 'c2': 'Green'}</s>