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<?php

function ccd_admin_notice() {
  global $current_user;

  $user_id = $current_user->ID;

  if ( ! get_user_meta( $user_id, 'ignore_notice' ) ) {
    echo '<div class="updated"><p>'; 
    printf( __( 'Thanks for choosing our theme! Please use the <strong><a href="' . get_admin_url() . 'customize.php' . '">theme customizer</a></strong> to customize your theme.' ), '?nag_ignore=0' );
    echo '</p></div>';
	}
}
add_action( 'admin_notices', 'ccd_admin_notice' );

function ccd_nag_ignore() {
	global $current_user;
  
  $user_id = $current_user->ID;

  if ( isset( $_GET['nag_ignore']) && '0' == $_GET['nag_ignore'] ) {
    add_user_meta( $user_id, 'ignore_notice', 'true', true );
  }
}
add_action( 'admin_init', 'ccd_nag_ignore' );

?>