Function std.range.dropBackExactly
Similar to drop and dropBack but they call
    range and popFrontExactly(n)range
    instead.
						
				R dropBackExactly(R)
				(
				
				  R range,
				
				  size_t n
				
				)
				
				if (isBidirectionalRange!R);
						
					
				Note
Unlike drop, dropExactly will assume that the
    range holds at least n elements. This makes dropExactly
    faster than drop, but it also means that if range does
    not contain at least n elements, it will attempt to call popFront
    on an empty range, which is undefined behavior. So, only use
    popFrontExactly when it is guaranteed that range holds at least
    n elements.
Parameters
| Name | Description | 
|---|---|
| range | the input range to drop from | 
| n | the number of elements to drop | 
Returns
See Also
std,
        std
Example
import stdAuthors
Andrei Alexandrescu, David Simcha, Jonathan M Davis, and Jack Stouffer. Credit for some of the ideas in building this module goes to Leonardo Maffi.