Duplicated graph heading #190
Description
When I set the heading property in the Network class, my graph gets rendered with a double heading.
To reproduce:
from pyvis.network import Network
net = Network(heading="My heading")
net.add_node(1, label="Node 1") # node id = 1 and label = Node 1
net.add_node(2) # node id and label = 2
net.show('net.html')I obtain the following behavior:
