Graphmath.Vec3.weighted_sum

You're seeing just the function weighted_sum, go back to Graphmath.Vec3 module for more information.
Link to this function

weighted_sum(a, arg1, b, arg2)

Specs

weighted_sum(number(), vec3(), number(), vec3()) :: vec3()

weighted_sum(a, v1, b, v2) returns the sum of vectors v1 and v2 having been scaled by a and b, respectively.