Merge pull request #107 from 30-seconds/fixes

Resolves #99
Resolves #103
Resolves #104

snippets/count_by.md

@@ -12,13 +12,12 @@ Iterate over the map and increase the element count each time it occurs.
 def count_by(arr, fn=lambda x: x):
   key = {}
   for el in map(fn, arr):
-    key[el] = 0 if el not in key else key[el]
-    key[el] += 1
+    key[el] = 1 if el not in key else key[el] + 1
   return key
 ```
 
 ```py
 from math import floor
-count_by([6.1, 4.2, 6.3], floor) # {4: 1, 6: 2}
+count_by([6.1, 4.2, 6.3], floor) # {6: 2, 4: 1}
 count_by(['one', 'two', 'three'], len) # {3: 2, 5: 1}
-```
+```

snippets/every.md

@@ -5,15 +5,11 @@ tags: list,function,intermediate
 
 Returns `True` if the provided function returns `True` for every element in the list, `False` otherwise.
 
-Iterate over the elements of the list to test if every element in the list returns `True` based on `fn`.
-Omit the seconds argument, `fn`, to check if all elements are `True`.
+Use `all()` in combination with `map` and `fn` to check if `fn` returns `True` for all elements in the list.
 
 ```py
-def every(lst, fn=lambda x: not not x):
-  for el in lst:
-    if not fn(el):
-      return False
-  return True
+def every(lst, fn=lambda x: x):
+  return all(map(fn, lst))
 ```
 
 ```py

snippets/group_by.md

@@ -5,7 +5,7 @@ tags: list,object,beginner
 
 Groups the elements of a list based on the given function.
 
-Use `list()` in combination with `map()` and `fn` to map the values of the list to the keys of an object.
+Use `map()` and `fn` to map the values of the list to the keys of an object.
 Use list comprehension to map each element to the appropriate `key`.
 
 ```py

snippets/max_by.md

@@ -5,11 +5,11 @@ tags: math,list,function,beginner
 
 Returns the maximum value of a list, after mapping each element to a value using the provided function.
 
-Use `map()` with `fn` to map each element to a value using the provided function, convert to a `list` and use `max()` to return the maximum value.
+Use `map()` with `fn` to map each element to a value using the provided function, use `max()` to return the maximum value.
 
 ```py
 def max_by(lst, fn):
-  return max(list(map(fn,lst)))
+  return max(map(fn,lst))
 ```
 
 ```py

snippets/min_by.md

@@ -5,11 +5,11 @@ tags: math,list,function,beginner
 
 Returns the minimum value of a list, after mapping each element to a value using the provided function.
 
-Use `map()` with `fn` to map each element to a value using the provided function, convert to a `list` and use `min()` to return the minimum value.
+Use `map()` with `fn` to map each element to a value using the provided function, use `min()` to return the minimum value.
 
 ```py
 def min_by(lst, fn):
-  return min(list(map(fn,lst)))
+  return min(map(fn,lst))
 ```
 
 ```py

snippets/none.md

@@ -5,15 +5,11 @@ tags: list,function,intermediate
 
 Returns `False` if the provided function returns `True` for at least one element in the list, `True` otherwise.
 
-Iterate over the elements of the list to test if every element in the list returns `False` based on `fn`.
-Omit the seconds argument, `fn`, to check if all elements are `False`.
+Use `all()` in combination with `map()` and `fn` to check if `fn` returns `False` for all the elements in the list.
 
 ```py
-def none(lst, fn=lambda x: not not x):
-  for el in lst:
-    if fn(el):
-      return False
-  return True
+def none(lst, fn=lambda x: x):
+  return all(map(lambda x: not fn(x), lst))
 ```
 
 ```py

snippets/some.md

@@ -5,15 +5,11 @@ tags: list,function,intermediate
 
 Returns `True` if the provided function returns `True` for at least one element in the list, `False` otherwise.
 
-Iterate over the elements of the list to test if every element in the list returns `True` based on `fn`.
-Omit the seconds argument, `fn`, to check if all elements are `True`.
+Use `any()` in combination with `map()` and `fn` to check if `fn` returns `True` for any element in the list.
 
 ```py
-def some(lst, fn=lambda x: not not x):
-  for el in lst:
-    if fn(el):
-      return True
-  return False
+def some(lst, fn=lambda x: x):
+  return any(map(fn, lst))
 ```
 
 ```py

snippets/sum_by.md

@@ -5,11 +5,11 @@ tags: math,list,function,beginner
 
 Returns the sum of a list, after mapping each element to a value using the provided function.
 
-Use `map()` with `fn` to map each element to a value using the provided function, convert to a `list` and use `sum()` to return the sum of the values.
+Use `map()` with `fn` to map each element to a value using the provided function, use `sum()` to return the sum of the values.
 
 ```py
 def sum_by(lst, fn):
-  return sum(list(map(fn,lst)))
+  return sum(map(fn,lst))
 ```
 
 ```py