Use dict.items() instead of explicitly accessing the values within the loop.

useItemsToIterateDict.ql

/**
 * @name Iterate of the items of a dictionary using `.items()`.
 * @description instead of iterating over the keys of a dictionary and the indexing the dictionary,
		use `.items()` to retrieve the key-value pairs.
 * @kind problem
 * @tags maintainability
 * @problem.severity recommendation
 * @sub-severity low
 * @precision medium
 * @tags speed
 * @sub-severity low
 * @id py/use-for-items
 */
import python

from For loop, Name dict
where
	loop.getIter() = dict and
	dict.pointsTo().getClass().getQualifiedName() = "dict" and
	exists(Subscript subs | 
      	loop.getBody().contains(subs) and        
        subs.getValue().(Name).pointsTo(dict.pointsTo()) and
 		subs.getIndex().(Name).getVariable() = loop.getTarget().(Name).getVariable() and
        // The dict[val] is *not* only assigned directly.
        not exists(AugAssign assignment | assignment.contains(subs) and assignment.getTarget() = subs) and
        not exists(AssignStmt assignment | assignment.contains(subs) and assignment.getATarget() = subs)
	)
select dict, "Use `.items()` to jointly iterate over the values of each `" + loop.getTarget().(Name).getVariable().getId() 
	+ "` in the dictionary `" + dict.getId() + "` instead of indexing the dictionary again."