user: ### 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
    
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Answer: {"fn_name": "pattern", "inputs": [[3], [15], [-3], [-25], [0]], "outputs": [["1   1\n 2 2 \n  3  \n 2 2 \n1   1"], ["1                           1\n 2                         2 \n  3                       3  \n   4                     4   \n    5                   5    \n     6                 6     \n      7               7      \n       8             8       \n        9           9        \n         0         0         \n          1       1          \n           2     2           \n            3   3            \n             4 4             \n              5              \n             4 4             \n            3   3            \n           2     2           \n          1       1          \n         0         0         \n        9           9        \n       8             8       \n      7               7      \n     6                 6     \n    5                   5    \n   4                     4   \n  3                       3  \n 2                         2 \n1                           1"], [""], [""], [""]]}