Function head() returns the first element of the array, namely, the element with index [0].

Arguments：

• Array <array>

Returns：

• First element <string>

Common Usage

Example: Find a 3-step path from Card CA002 to CA005, and return the 1st edge of the path.

n({_id == "CA002"}).e()[3].n({_id == "CA005"}).limit(1) as p
return head(pedges(p))