input: Write a python function to filter a list of dictionaries by a given key and value.
  assert filter_by_key_value([{'name': 'apple', 'price': 1.2}, {'name': 'banana', 'price': 0.5}], 'name', 'apple') == [{'name': 'apple', 'price': 1.2}]
  assert filter_by_key_value([{'name': 'apple', 'price': 1.2}, {'name': 'banana', 'price': 0.5}], 'price', 0.5) == [{'name': 'banana', 'price': 0.5}]
  assert filter_by_key_value([{'name': 'apple', 'price': 1.2}, {'name': 'banana', 'price': 0.5}], 'name', 'orange') == []
output: def filter_by_key_value(dict_list, key, value):
      return [d for d in dict_list if d.get(key) == value]