Snippet for adding new bootstrap rows in the loop

rows_in_the_loop.php

<?php

				// check if the repeater field has rows of data
				if( have_rows('staff_member') ):

					$i = 0;

				 	// loop through the rows of data
				    while ( have_rows('staff_member') ) : the_row(); ?>

				    <?php

						if($i % 4 == 0) { ?> 
        					<div class="row d-flex">
   						<?php
   							}

   							?>

						<div class = "col-md-3 mb-4">
					        <img class = "staff_headshot mb-3" src = "<?php the_sub_field('headshot'); ?>">
					        <h3 class = "staff_name"><?php the_sub_field('name'); ?></h3>
					        <p class = "staff_bio"><?php the_sub_field('bio'); ?></p>
					        <a class = "staff_email" href = "mailto:<?php the_sub_field('e-mail_address'); ?>"><i class="fa fa-envelope" aria-hidden="true"></i><?php the_sub_field('e-mail_address'); ?></a>
					        <p class = "staff_phone"><i class="fa fa-phone" aria-hidden="true"></i><?php the_sub_field('phone_number'); ?></p>
					        </div>

				        <?php 
				    $i++;
    				if($i != 0 && $i % 4 == 0) { ?> 
       				</div><!-- end of row -->
    				<?php
    				}

				    endwhile;

				else :

				    // no rows found

				endif;

				?>