Your job is to build a function which determines whether or not there are double characters in a string (including whitespace characters). For example ```aa```, ``!!`` or ```  ```.
 

You want the function to return true if the string contains double characters and false if not.  The test should not be case sensitive; for example both ```aa``` & ```aA``` return true.

Examples:
```python
  double_check("abca")
  #returns False
  
  double_check("aabc")
  #returns True
  
  double_check("a 11 c d")
  #returns True
  
  double_check("AabBcC")
  #returns True
  
  double_check("a b  c")
  #returns True
  
  double_check("a b c d e f g h i h k")
  #returns False
  
  double_check("2020")
  #returns False
  
  double_check("a!@€£#$%^&*()_-+=}]{[|\"':;?/>.<,~")
  #returns False
```

Difficulty: introductory

Starter code:

def double_check(strng):
	

Solutions:
import re

def double_check(str):
    return bool(re.search(r"(.)\1", str.lower()))

def double_check(str):
    str = str.lower()
    c1 = ''
    for c in str:
      if c == c1:
        return True
      c1 = c
    return False

from itertools import groupby


def double_check(s):
    return any(sum(1 for _ in g) == 2 for _, g in groupby(s.lower()))


import re

def double_check(s):
    return bool(re.search(r'(.)\1', s.lower()))

def double_check(inp):
    inp = inp.lower()
    return any(i == j for i, j in zip(inp[:-1], inp[1:]))

double_check = lambda s: bool(__import__('re').search(r'(?i)(.)\1',s))

def double_check(strng):
    s = strng.upper()
    return any([s[i] == s[i+1] for i in range(len(strng) - 1)])

import re

def double_check(strng):
    return bool(re.search(r"(.)\1", strng, re.IGNORECASE))

def double_check(strng):
    for idx in range(len(strng)-1):
        if strng[idx].lower() == strng[idx+1].lower():
            return True
    return False

def double_check(strng):
    c_ = None
    for c in strng.upper():
        if c == c_: return True
        c_ = c
    return False

import re
def double_check(s):
    return re.search(r'(?i)(.)\1', s) != None

def double_check(strng):
    strng = strng.lower()
    l = []
    for x in strng:
            if x*2 in strng:
                    l.append(True)
    return bool(l)

def double_check(s):
    return any(prev_val.lower() == next_val.lower() for prev_val, next_val in zip(s, s[1:]))

def double_check(strng):
    return bool(sum([strng.lower()[i-1] == strng.lower()[i] for i in range(1,len(strng))]))

double_check=lambda strng: any(x.lower()==strng[i+1].lower() for i,x in enumerate(strng[:-1]))

import re
def double_check(strng):
    return True if re.findall(r"(.)\1", strng.lower()) else False

def double_check(strng):
    for i in set(strng):
        if i*2 in strng.lower(): return True
    return False

import re
def double_check(strng):
    pattern = re.compile(r'(.)\1', re.IGNORECASE)
    return bool(re.search(pattern, strng))

def double_check(strng):
    prev_char = strng[0]
    for char in strng[1:].lower():
        if char == prev_char:
            return True
        prev_char = char
    return False

def double_check(strng):
    for i in set(strng.lower()):
        if strng.lower().count(i*2)>=1:
            return True
    return False