WordPress Option Tree setup for theme option

functions.php

<?php

  //option tree setup for theme option
  //first download option tree plugin from wordpress.org then paste the folder in theme directory.
  //copy 2 files “theme-options.php” and “meta-boxes.php” to inc folder then include.
  add_filter( 'ot_show_pages', '__return_false' );
  add_filter( 'ot_show_new_layout', '__return_false' );
  add_filter( 'ot_theme_mode', '__return_true' );
  include_once( 'option-tree/ot-loader.php' );
  include_once( 'inc/theme-options.php' );
  //Custom Meta Box
  include_once('inc/v-meta-boxes.php');
?>

header.php

//finally calling it from header.php
<a href="<?php echo esc_url( home_url( '/' ) ); ?>">
<?php $logo = get_option_tree( 'logo', '', false ); ?>
	<?php if($logo) : ?>
            <img src="<?php echo $logo;?>"/>
            <?php else : ?>
            <img src="<?php echo get_template_directory_uri()?>/img/e24logo.png ?>" alt="">
            <?php endif; ?>
</a>

theme-options.php

//adding logo option
//adding a section on theme-options.php
    'sections'        => array( 
      array(
        'id'          => 'header',
        'title'       => __( 'Logo', 'e24' )
      )
    ),
//adding the settings for it
      'settings'        => array(
      array(
        'label'       => 'Upload The Logo.',
        'id'          => 'logo',
        'type'        => 'upload',
        'section'     => 'header',
        'desc'        => 'Upload your logo here. Recommended logo size is 125x40. However, if you want to insert bigger size, no problem, just maintain the ratio. So if you want a 2x logo insert 250x80, if you want a 4x logo insert 500x160.'
      ), 
    )