IEnumerable.join Method
        
 Correlates the elements of two sequences based on matching keys.  If "equalityComparer"
 is not provided, the default comparer is used to compare keys.
 
         
        Parameters
        
            - inner
            
 
            - 
                
Type: IEnumerable
The sequence to join to the first sequence. 
            - outerKeySelector
            
 
            - 
                
Type: Function
A function to extract the join key from each element of the first sequence. 
            - innerKeySelector
            
 
            - 
                
Type: Function
A function to extract the join key from each element of the second sequence. 
            - resultSelector
            
 
            - 
                
Type: Function
A function to create a result element from two matching elements.
Optional: True 
            - equalityComparer
            
 
            - 
                
Type: IEqualityComparer
An equality comparer to compare join keys.
Optional: True 
        
        Return Value
        
Type: IEnumerable
        
An enumerable that has elements obtained by performing an inner join on two sequences.