Mobile Unity Shader - how to work with on/off boolean

Question

How do you set a boolean for a shader? How do you write a conditional or assign a boolean in a shader?

So, it seems that shaders do not take booleans... so I tried assigning the float to 0 or 1 ren.material.SetFloat("_ZWriteVal", 1f);, but it doesn't seem to work...

 Shader "ZTestLess"
{

 Properties {
_Color ("Color", Color) = (0,0,0)
[Toggle(Z_WRITE_VAL)] 
_ZWriteVal("Z Write Val", Float) = 0
}

SubShader
 {
    Tags { "Queue" = "Background" }

    Pass
    {
        CGPROGRAM
        #pragma shader_feature Z_WRITE_VAL

         #ifdef Z_WRITE_VAL
            ZWrite On
         #else 
            ZWrite Off

           ZTest Less
            Color [_Color]
            Lighting Off 

         ENDCG
    }
}
}