Storing a value inside a collection at a given key or index and then unconditionally overwriting it without reading the initial value is a case of
a "dead store".
def swap(mylist, index1, index2):
tmp = mylist[index2]
mylist[index2] = mylist[index1]
mylist[index2] = tmp # Noncompliant
list2 = [0,1,2,3,4,5,6,7,8,9]
list2[3:5] = [42,42]
list2[3:5] = [42,42] # Noncompliant
mymap = {'a': {}}
mymap['a']['b'] = 42
mymap['a']['b'] = 42 # Noncompliant
This practice is redundant and will cause confusion for the reader. More importantly, it is often an error and not what the developer intended to
do.
