Render blocks of text one or more times, depending on the value of the key in the current context.
A key that references a value within the current or parent [can.stache.context context]. If the value is a function or can.compute, the function's return value is used.
Depending on the value's type, the following actions happen:
Arrayor can.List - the block is rendered for each item in the array. The [can.stache.context context] is set to the item within each block rendering.
truthyvalue - the block is rendered with the [can.stache.context context] set to the value.
falseyvalue - the block is not rendered.
The rendered result of the blocks, block or an empty string is returned.