strip-units(100px) // 100
strip-units(18em)  // 18

is-bool(true)     //returns true
is-bool(false)    //returns true
is-bool(test)     //returns false
is-bool(1)        //returns false
is-bool(null)     //returns false

is-color(#333)     //returns true
is-color(black)    //returns true
is-color(test)     //returns false

is-empty('')        //returns true
is-empty(())        //returns true
is-empty('test')    //returns false

is-float(-1.5)	//returns true
is-float(1.5)     //returns true
is-float(1)		//returns false
is-float(1em) 	//returns false
is-float(0) 	    //returns false

is-integer(1)		 //returns true
is-integer(0)		 //returns true
is-integer(-50)    //returns true
is-integer(1.5)	 //returns false
is-integer(1em)	 //returns false

is-list(a b)             //returns true
is-list(1 2 3)           //returns true
is-list((test, test))	   //returns true
is-list(test)            //returns false
is-list(1)               //returns false

is-map(a: 1, b: 2)   	  //returns true
is-map(1 2 3)        	  //returns false
is-map((test, test))    //returns false
is-map(test)         	  //returns false
is-map(1)            	  //returns false

is-measure-negative(-10em)   	 //returns true
is-measure-negative(0px)     	 //returns false
is-measure-negative(0)       	 //returns false
is-measure-negative(777rem)    //returns false

is-measure-positive(10px)   	 //returns true
is-measure-positive(0px)   	 //returns false
is-measure-positive(0)   		 //returns false
is-measure-positive(-777px)    //returns false

is-measure(1px) 	  //returns true
is-measure(5em)     //returns true
is-measure(5)       //returns false
is-measure(test)    //returns false
is-measure(em)      //returns false

is-negative(-5)        //returns true
is-negative(-10px)     //returns false
is-negative(300)       //returns false
is-negative('test')    //returns false
is-negative(0)         //returns false

is-null(null)    	  //returns true
is-null(false)   	  //returns false
is-null(0)       	  //returns false
is-null('hello')    //returns false
is-null(113)        //returns false

is-number(1)   				   //returns true
is-number('1') 	               //returns false
is-number(1em)    			   //returns false
is-number('sassy-validation')    //returns false

is-positive(1)          //returns true
is-positive(0)          //returns false
is-positive(-1)    	  //returns false
is-positive('hello')    //returns false

is-string('sassy-validation')    //returns true
is-string(1)    	 			   //returns false
is-string(18px)    	 		   //returns false

is-unit(rem)    			     //returns true
is-unit(-1000px) 	   			 //returns false
is-unit('sassy-validation')    //returns false
is-unit(777) 		   			 //returns false

validate(1em, measure)     		// returns true
validate(100, number positive)    // returns true
validate(1, number)        	    // returns true
validate(1, string)        	    // returns false