code: func interpolationFuncMax() ast.Function {
  	return ast.Function{
  		ArgTypes:     []ast.Type{ast.TypeFloat},
  		ReturnType:   ast.TypeFloat,
  		Variadic:     true,
  		VariadicType: ast.TypeFloat,
  		Callback: func(args []interface{}) (interface{}, error) {
  			max := args[0].(float64)
  
  			for i := 1; i < len(args); i++ {
  				max = math.Max(max, args[i].(float64))
  			}
  
  			return max, nil
  		},
  	}
  }
docs: // interpolationFuncMax returns the maximum of the numeric arguments