Returns a lambda function defined as:
sumFrom : (+, iterable) => lambda : (convert : object => number) => number
It is then possibly to curry this function by selecting the convert function that defines of each item must be converted in a number.
This is done by invoking on that returned object the method that returns the values of the property to be summed as in the following example
int totalAge = sumFrom(persons).getAge();
The actual class of T is inferred from the class of the first iterable's item, but you can
specify a particular class by using the overloaded method.