Travis CI: Add a flake8 test for unused imports

.travis.yml

@@ -6,7 +6,7 @@ before_install: pip install --upgrade pip setuptools
 install: pip install -r requirements.txt
 before_script:
   - black --check . || true
-  - flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
+  - flake8 . --count --select=E9,F401,F63,F7,F82 --show-source --statistics
 script:
   - mypy --ignore-missing-imports .
   #- IGNORE="data_structures,file_transfer_protocol,graphs,machine_learning,maths,neural_network,project_euler"

graphs/bfs.py

@@ -16,10 +16,19 @@
 
 """
 
-import collections
+G = {'A': ['B', 'C'],
+     'B': ['A', 'D', 'E'],
+     'C': ['A', 'F'],
+     'D': ['B'],
+     'E': ['B', 'F'],
+     'F': ['C', 'E']}
 
 
 def bfs(graph, start):
+    """
+    >>> ''.join(sorted(bfs(G, 'A')))
+    'ABCDEF'
+    """
     explored, queue = set(), [start]  # collections.deque([start])
     explored.add(start)
     while queue:
@@ -31,11 +40,5 @@ def bfs(graph, start):
     return explored
 
 
-G = {'A': ['B', 'C'],
-     'B': ['A', 'D', 'E'],
-     'C': ['A', 'F'],
-     'D': ['B'],
-     'E': ['B', 'F'],
-     'F': ['C', 'E']}
-
-print(bfs(G, 'A'))
+if __name__ == '__main__':
+    print(bfs(G, 'A'))

maths/volume.py

@@ -6,8 +6,6 @@
 
 from math import pi
 
-PI = pi
-
 
 def vol_cube(side_length):
     """Calculate the Volume of a Cube."""
@@ -39,9 +37,7 @@ def vol_right_circ_cone(radius, height):
     volume = (1/3) * pi * radius^2 * height
     """
 
-    import math
-
-    return (float(1) / 3) * PI * (radius ** 2) * height
+    return (float(1) / 3) * pi * (radius ** 2) * height
 
 
 def vol_prism(area_of_base, height):
@@ -71,7 +67,7 @@ def vol_sphere(radius):
     V = (4/3) * pi * r^3
     Wikipedia reference: https://en.wikipedia.org/wiki/Sphere
     """
-    return (float(4) / 3) * PI * radius ** 3
+    return (float(4) / 3) * pi * radius ** 3
 
 
 def vol_circular_cylinder(radius, height):
@@ -80,7 +76,7 @@ def vol_circular_cylinder(radius, height):
     Wikipedia reference: https://en.wikipedia.org/wiki/Cylinder
     volume = pi * radius^2 * height
     """
-    return PI * radius ** 2 * height
+    return pi * radius ** 2 * height
 
 
 def main():