Use copy() to copy os.env rather than dict()

as it is more explicit.

Author: tomc271

src/boutdata/__init__.py

@@ -1,4 +1,4 @@
-""" Routines for exchanging data to/from BOUT++ """
+"""Routines for exchanging data to/from BOUT++"""
 
 from boutdata.collect import attributes, collect
 from boututils.boutarray import BoutArray

src/boutdata/gen_surface.py

@@ -1,6 +1,4 @@
-"""Flux surface generator for tokamak grid files
-
-"""
+"""Flux surface generator for tokamak grid files"""
 
 from __future__ import print_function
 

src/boutdata/griddata.py

@@ -1,6 +1,4 @@
-"""Routines for manipulating grid files
-
-"""
+"""Routines for manipulating grid files"""
 
 import matplotlib.pyplot as plt
 import numpy as np

src/boutdata/input.py

@@ -1,6 +1,4 @@
-"""Fourier transform data for input to BOUT++
-
-"""
+"""Fourier transform data for input to BOUT++"""
 
 from numpy import ndarray
 from numpy.fft import rfft

src/boutdata/mms.py

@@ -1,5 +1,5 @@
-""" Functions for calculating sources for the
-    Method of Manufactured Solutions (MMS)
+"""Functions for calculating sources for the
+Method of Manufactured Solutions (MMS)
 
 """
 

src/boutdata/settings.py

@@ -1,6 +1,4 @@
-"""Parse BOUT.inp settings file
-
-"""
+"""Parse BOUT.inp settings file"""
 
 
 def get(filename, name, section=None):

src/boutdata/tests/test_boutoptions.py

@@ -210,16 +210,14 @@ def test_str():
     options["other top-level"] = 3
 
     # lstrip to remove the first empty line
-    expected = textwrap.dedent(
-        """
+    expected = textwrap.dedent("""
         top-level value = 0
         other top-level = 3
 
         [section]
         first = 1
         second = 2
-        """
-    ).lstrip()
+        """).lstrip()
 
     assert str(options) == expected
 

src/boututils/__init__.py

@@ -1,4 +1,4 @@
-""" Generic routines, useful for all data """
+"""Generic routines, useful for all data"""
 
 __all__ = []
 __name__ = "boututils"

src/boututils/ask.py

@@ -1,6 +1,4 @@
-"""Ask a yes/no question and return the answer.
-
-"""
+"""Ask a yes/no question and return the answer."""
 
 import sys
 

src/boututils/boutarray.py

@@ -1,6 +1,4 @@
-"""Wrapper for ndarray with extra attributes for BOUT++ fields.
-
-"""
+"""Wrapper for ndarray with extra attributes for BOUT++ fields."""
 
 import numpy