Variable(node) {
            if (node.name.value === variableName) {
              variableUseCount = variableUseCount + 1;
            }
          }
1. Find the current variable definition in the operation def
2. Extract its value
3. Replace the current arg value
4. Visit the resulting operation to see if there are any other usages of the variable
5. If not, remove the variableDefinition