text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2018 The Stdlib Authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *    http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
  
  'use strict';
  
  // MODULES //
  
  var format = require( 'd3-format' ).format; // TODO: remove
  var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
  var isNull = require( '@stdlib/assert/is-null' );
  var identity = require( '@stdlib/utils/identity-function' );
  
  
  // MAIN //
  
  /**
  * Returns the axis tick format.
  *
  * @private
  * @returns {Function} format function
  */
  function get() {
  	/* eslint-disable no-invalid-this */
  	if ( isString( this._tickFormat ) ) {
  		return format( this._tickFormat );
  	}
  	if ( isNull( this._tickFormat ) ) {
  		if ( this._scale.tickFormat ) {
  			return this._scale.tickFormat( this._numTicks, this._tickFormat );
  		}
  		return identity;
  	}
  	return this._tickFormat;
  }
  
  
  // EXPORTS //
  
  module.exports = get;
  