static _createSampleAndBlendFunctionSignature(imageryFlags) {
    const functionId = "sampleAndBlend";
    const parameters = [];
    parameters.push(`vec4 previousColor`);
    parameters.push(`sampler2D textureToSample`);
    parameters.push(`vec2 textureCoordinates`);
    parameters.push(`vec4 textureCoordinateRectangle`);
    parameters.push(`vec4 textureCoordinateTranslationAndScale`);
    if (imageryFlags.alpha) {
      parameters.push(`float textureAlpha`);
    }
    if (imageryFlags.brightness) {
      parameters.push(`float textureBrightness`);
    }
    if (imageryFlags.contrast) {
      parameters.push(`float textureContrast`);
    }
    if (imageryFlags.hue) {
      parameters.push(`float textureHue`);
    }
    if (imageryFlags.saturation) {
      parameters.push(`float textureSaturation`);
    }
    if (imageryFlags.gamma) {
      parameters.push(`float textureOneOverGamma`);
    }
    if (imageryFlags.colorToAlpha) {
      parameters.push(`vec4 colorToAlpha`);
    }
    const parametersString = parameters.join(", ");

    const signature = `vec4 ${functionId}(${parametersString})`;
    return signature;
  }
Create the function signature for the `sampleAndBlend` function,
based on the features that are required for the imagery.

For details, see `buildSampleAndBlendFunction`

@param {ImageryFlags} imageryFlags The imagery flags
@returns {string} The string