### Task:
You have to write a function `pattern` which returns the following Pattern(See Examples) upto (2n-1) rows, where n is parameter.
* Note:`Returning` the pattern is not the same as `Printing` the pattern.
#### Parameters:
    pattern(        n        );
                    ^                     
                    |                     
             Term upto which   
           Basic Pattern(this)     
                should be         
                 created            
#### Rules/Note:
* If `n < 1` then it should return "" i.e. empty string.
* `The length of each line is same`, and is equal to the length of longest line in the pattern i.e (2n-1).
* Range of Parameters (for the sake of CW Compiler) :
  + `n ∈ (-∞,100]`
### Examples:
* pattern(5):
        1       1
         2     2 
          3   3  
           4 4   
            5    
           4 4   
          3   3  
         2     2 
        1       1
* pattern(10):
        1                 1
         2               2 
          3             3  
           4           4   
            5         5    
             6       6     
              7     7      
               8   8       
                9 9        
                 0         
                9 9        
               8   8       
              7     7      
             6       6     
            5         5    
           4           4   
          3             3  
         2               2 
        1                 1
* pattern(15):
        1                           1
         2                         2 
          3                       3  
           4                     4   
            5                   5    
             6                 6     
              7               7      
               8             8       
                9           9        
                 0         0         
                  1       1          
                   2     2           
                    3   3            
                     4 4             
                      5              
                     4 4             
                    3   3            
                   2     2           
                  1       1          
                 0         0         
                9           9        
               8             8       
              7               7      
             6                 6     
            5                   5    
           4                     4   
          3                       3  
         2                         2 
        1                           1
[List of all my katas]("http://www.codewars.com/users/curious_db97/authored")
get_r = lambda y: str((y + 1) % 10)
row = lambda n, i: ' ' * i + get_r(i) + ' ' * max(0, 2 * n - 3 - i * 2) + (get_r(i) if i != n - 1 else '') + ' ' * i
def pattern(n):
  if n < 1: return ''
  top = [row(n, x) for x in range(n - 1)]
  return '\n'.join(top + [row(n, n - 1)] + list(reversed(top)))
get_r = lambda y: str((y + 1) % 10)
row = lambda n, i: ' ' * i + get_r(i) + ' ' * max(0, 2 * n - 3 - i * 2) + (get_r(i) if i != n - 1 else '') + ' ' * i
def pattern(n):
  if n < 1: return ''
  top = [row(n, x) for x in range(n - 1)]
  return '\n'.join(top + [row(n, n - 1)] + list(reversed(top)))