Additional call syntaxes

[cliffckerr]

# Provide as function
import subenv
env = subenv.Env() # use default python interpreter

def my_func():
  import starsim as ss
  sim = ss.demo()
  return sim

sim = env(my_func) # or env(sim=my_func).get('sim')

# Execute from within the file
import subenv
env = subenv.Env()

# <start>
import starsim as ss
sim = ss.demo()
# <stop>

env.run_lines(start='<start>', stop='<stop>')
sim = env['sim']