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You can visualize the structure of your flow using the visualize() method.
Install GraphvizTo use the visualize() method, you must have Graphviz installed. Please follow the Graphviz installation instructions for your platform.
from prefect import flow, task

@task(name="Print Hello")
def print_hello(name):
    msg = f"Hello {name}!"
    print(msg)
    return msg

@task(name="Print Hello Again")
def print_hello_again(name):
    msg = f"Hello {name}!"
    print(msg)
    return msg

@flow(name="Hello Flow")
def hello_world(name="world"):
    message = print_hello(name)
    message2 = print_hello_again(message)

if __name__ == "__main__":
    hello_world.visualize()
A simple flow visualized with the .visualize() method
Calling visualize() will execute code outside of tasksCode outside of tasks will run when calling visualize(). To avoid inadvertent execution, place code you don’t want to run in tasks.
For workflows with dynamic structure using loops and/or if/else statements, you can provide tasks with mock return values for use in the visualize() call to choose which code paths to visualize. 
from prefect import flow, task
@task(viz_return_value=[4])
def get_list():
    return [1, 2, 3]

@task
def append_one(n):
    return n.append(6)

@flow
def viz_return_value_tracked():
    l = get_list()
    for num in range(3):
        l.append(5)
        append_one(l)

if __name__ == "__main__":
    viz_return_value_tracked.visualize()
A flow with return values visualized with the .visualize() method