Design an algorithm in Python that takes a list of strings and returns the list of strings in decreasing order of length.
["Hello", "World", "This", "is", "a", "test"]
def order_by_length(input_list):
  return sorted(input_list, key=len, reverse=True)
  
input_list = ["Hello", "World", "This", "is", "a", "test"]
print(order_by_length(input_list))