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