sum function:

Sum all the items in the list. If list have non numeric items, it will return nuthing. One can filter with number? to ensure there is a result.

Examples:

• running: (sum [1, 5, 1.1]) will give: 7.1

• running: (sum []) will give: 0

• running: (sum [1, 5, 1.1, "text"]) will return nothing