src/IteratorPipeline/Traits/MappingTrait.php
public function column($valueColumn, $keyColumn = null)
    {
        return $this->then(i\iterable_column, $valueColumn, $keyColumn);
    }
public function column($valueColumn, $keyColumn = null)
    {
        return $this->then(i\iterable_column, $valueColumn, $keyColumn);
    }
Return the values from a single column / property.
Create key/value pairs by specifying the key.

@param string|int|null $valueColumn  null to keep values
@param string|int|null $keyColumn    null to keep keys
@return static