Jupyter notebook magic for plantuml using web service

plantumlmagic.py

"""Save the file where you can import it in your jupyter notebook.

In a cell, execute:
import plantumlmagic
%reload_ext plantumlmagic

Then you can use the magic in another cell:
%%plantumlmagic localhost:1234
@startuml
Bob -> Alice : hello
@enduml

Assuming you have a plantuml service running on localhost port 1234.
If you don't provide localhost:1234 it will use the service on plantuml.com.
It also requires plantuml package.

You can easily setup a plantuml service using a docker container:
docker run -d --name plantuml -p 1234:8080 plantuml/plantuml-server:tomcat
"""
import plantuml
from IPython.core.magic import magics_class, cell_magic, Magics
from IPython.display import Image, SVG

@magics_class
class Plantumlmagic(Magics):

    @cell_magic
    def plantumlmagic(self, line, cell):
        if line:
            pu = plantuml.PlantUML(url="http://{0}/svg/".format(line))
        else:
            pu = plantuml.PlantUML(url="http://www.plantuml.com/plantuml/svg/")
        self.code = ""
        for line in cell.split('\n'):
            newline = line.strip()
            if newline:
                self.code += newline + '\n'
        return SVG(pu.processes(self.code))

def load_ipython_extension(ipython):
    ipython.register_magics(Plantumlmagic)