Approve functions used as default arguments (#4699)

* Approve functions used as default argumenets

* The default value for **seed** is the result of a function call

The default value for **seed** is the result of a function call which is not normally recommended and causes flake8-bugbear to raise a B008 error. However, in this case, it is accptable because `LinearCongruentialGenerator.__init__()` will only be called once per instance and it ensures that each instance will generate a unique sequence of numbers.

* The default value for **backend** is the result of a function call

The default value for **backend** is the result of a function call which is not normally recommended and causes flake8-bugbear to raise a B008 error. However, in this case, it is accptable because `Aer.get_backend()` is called when the function is definition and that same backend is then reused for function calls.

* Update linear_congruential_generator.py

* Update ripple_adder_classic.py

* Update ripple_adder_classic.py

* Update ripple_adder_classic.py

* Update ripple_adder_classic.py

* Update ripple_adder_classic.py

Author: cclauss

Diff for: other/linear_congruential_generator.py

@@ -8,7 +8,13 @@ class LinearCongruentialGenerator:
     A pseudorandom number generator.
     """
 
-    def __init__(self, multiplier, increment, modulo, seed=int(time())):
+    # The default value for **seed** is the result of a function call which is not
+    # normally recommended and causes flake8-bugbear to raise a B008 error. However,
+    # in this case, it is accptable because `LinearCongruentialGenerator.__init__()`
+    # will only be called once per instance and it ensures that each instance will
+    # generate a unique sequence of numbers.
+
+    def __init__(self, multiplier, increment, modulo, seed=int(time())):  # noqa: B008
         """
         These parameters are saved and used when nextNumber() is called.
 

Diff for: quantum/ripple_adder_classic.py

@@ -53,8 +53,16 @@ def full_adder(
     circuit.cx(input1_loc, input2_loc)
 
 
+# The default value for **backend** is the result of a function call which is not
+# normally recommended and causes flake8-bugbear to raise a B008 error. However,
+# in this case, this is accptable because `Aer.get_backend()` is called when the
+# function is defined and that same backend is then reused for all function calls.
+
+
 def ripple_adder(
-    val1: int, val2: int, backend: BaseBackend = Aer.get_backend("qasm_simulator")
+    val1: int,
+    val2: int,
+    backend: BaseBackend = Aer.get_backend("qasm_simulator"),  # noqa: B008
 ) -> int:
     """
     Quantum Equivalent of a Ripple Adder Circuit
@@ -63,7 +71,7 @@ def ripple_adder(
     Currently only adds 'emulated' Classical Bits
     but nothing prevents us from doing this with hadamard'd bits :)
 
-    Only supports adding +ve Integers
+    Only supports adding positive integers
 
     >>> ripple_adder(3, 4)
     7
@@ -99,7 +107,7 @@ def ripple_adder(
     res = execute(circuit, backend, shots=1).result()
 
     # The result is in binary. Convert it back to int
-    return int(list(res.get_counts().keys())[0], 2)
+    return int(list(res.get_counts())[0], 2)
 
 
 if __name__ == "__main__":