Create the function ```consecutive(arr)``` that takes an array of integers and return the minimum number of integers needed to make the contents of ```arr``` consecutive from the lowest number to the highest number.
For example:  If ```arr``` contains [4, 8, 6] then the output should be 2 because two numbers need to be added to the array (5 and 7) to make it a consecutive array of numbers from 4 to 8. Numbers in ```arr``` will be unique.

Difficulty: introductory

Starter code:

def consecutive(arr):
	

Solutions:
def consecutive(arr):
    return max(arr) - min(arr) + 1 - len(arr) if arr else 0

def consecutive(arr):
    #your code here
    if len(arr) == 1 or len(arr) == 0:
        return 0
    mn, mx = min(arr), max(arr)
    s = set(arr)
    return mx - mn - len(s) + 1

consecutive=lambda a:len(a)and-~max(a)-min(a)-len(a)

def consecutive(arr):
    try:
        return max(arr) - min(arr) - len(arr) + 1
    except:
        return 0

def consecutive(arr):
    if len(arr) <= 1:
        return 0
    return (max(arr) - min(arr) + 1) - len(arr)

def consecutive(arr):
    if len(arr)<2 :
        return 0;
    arr.sort();
    return arr[-1]-arr[0]-len(arr)+1;

def consecutive(arr):
  l = len(arr)
  return max(arr) - min(arr) + 1 - l if l>1 else 0

def consecutive(arr):
    arr = sorted(arr)
    return arr[-1] - arr[0] - len(arr[1:]) if len(arr) > 0 else 0

def consecutive(arr):
    if not arr:
        return 0
    return max(max(arr)-min(arr)-len(arr)+1,0)

def consecutive(arr):
    return len(range(min(arr),max(arr)+1))-len(arr) if arr else 0