Here we have a hash of people
with their house numbers:
| Name | House number |
|---|
| John | 507 |
| Sally | 239 |
| Adam | 786 |
| Nancy | 324 |
| Kelly | 788 |
Our task is to find every
person who has a house with
a house number greater than 500.
We can use select to do this.
Using select, we can get a smaller
part of the original hash.
select will only select the elements
for which the condition is true.
In this case, the condition is
that the house number
should be more than 500.
It's important to note that when select is used then
the "do end" block should return either true or false.
If the block returns true, then that key and value pair will
be selected and if the block returns false, then that key and
value pair will be rejected.