anchor: Shader:hasUniform
  Gets whether a uniform / extern variable exists in the Shader.
  
  If a graphics driver's shader compiler determines that a uniform / extern variable doesn't affect the final output of the shader, it may optimize the variable out. This function will return false in that case.
  hasuniform = Shader:hasUniform( name )
  name string The name of the uniform variable.
  hasuniform boolean Whether the uniform exists in the shader and affects its final output.