Grammar fixes + updates to Python on Mac instructions

INSTALL-Python3.md

@@ -1,33 +1,19 @@
 
 # Install Python 3.x
 
-Getting your Python setup right on your system is important.
-Otherwise you find yourself in the realm of confusing error messages.
-This documents focuses on getting Python 3 up and running on
-Debian/Ubuntu Linux based systems as well as on macOS via MacPorts.
-Your milleage may very.
+Getting your Python setup right on your system is important; otherwise, you may find yourself in the realm of confusing error messages.  The following instructions focus on getting Python 3 running on Debian/Ubuntu Linux-based systems as well as on macOS via MacPorts or HomeBrew.
 
-> If you are running on an Intel style processor (e.g. most Macs and Windows
-> machines) you can use a Python distribution called [Miniconda](https://docs.conda.io/en/latest/miniconda.html).
-> This is often the easiest approach to getting a modern Python on your machine. Otherwise continue
-> on reading.
+_**Tip**: If you are running on an Intel-based computers (e.g., most Macs and Windows machines), you can use a Python distribution called [Miniconda](https://docs.conda.io/en/latest/miniconda.html).  This is often the easiest approach to getting a modern Python on your machine.  If that's not suitable for you for any reason, continue on reading._
 
 ## Python versions issues
 
-It is possible to use your default OS provided python if it is version
-greater than 3.x. Many distributions still ship with version 2.7 out of the box
-and pipy's pip corresponding to version 2.7. On some systems, a version of 3.x
-is available using the commands `python3` and `pip3`. Others let you install 
-Python 3 and its pip via their package manager and use the package manager
-select default versions and/or names. This is true on Debian/Ubuntu based systems as
-well as macOS's MacPorts.
+It is possible to use your default OS-provided Python if it is version greater than 3.x. Many distributions still ship with version 2.7 out of the box and with `pip` command versions corresponding to version 2.7. On some systems, a version of 3.x is available using the commands `python3` and `pip3`. Others let you install Python 3 and `pip` via their package manager and use the package manager select default versions and/or names. This is true on Debian/Ubuntu based systems as well as macOS's MacPorts.
 
-
-## Getting the right Python and Pip
+## Getting the right Python and `pip`
 
 ### Debian/Ubuntu
 
-Debian based systems still ship with older versions of Python by
+Debian-based systems still ship with older versions of Python by
 default. We want to use a modern Python 3.x. Make sure it is 
 installed and available along with the related version of pip.
 
@@ -37,24 +23,31 @@ sudo apt install python3 python3-pip
 
 ### macOS with MacPorts
 
-If you are using macOS and MacPorts you can take a similar
-approach (presumably Homebrew for macOS uses the Debian
-style commands)
+If you are using macOS and MacPorts you can take a similar approach:
 
 ```
-sudo port install python38
+sudo port install python3
 sudo port install py38-pip
 ```
 
-At this point you should be able to envoke the Python interpreter
-using the `python3` command. You should see the version
-of python and pip with these commands.
+At this point you should be able to envoke the Python interpreter using the `python3` command. You should see the version of Python and `pip` with these commands:
 
 ```
 python3 --version
 python3 -m pip --version
 ```
 
+### macOS with HomeBrew
+
+If you are using macOS and HomeBrew, the corresponding commands are as follows:
+
+```
+sudo brew install python3
+```
+
+HomeBrew's Python 3 package installs `pip3` by default.  Unless you configured your copy of HomeBrew to install it elsewhere, programs should end up in `/usr/local/bin` on your computer.  Look for a version of `pip` there (e.g., by running the command `ls /usr/local/bin/pip*` to see what gets listed).
+
+
 ### Install Python modules using the right pip
 
 Often you'll need some additional modules with your