trying to contrive egs showing redirecting stdout (fd1) is different from writing to fd3+

--
	- eg1.1
		fish code:
			begin
				if isatty 1
					echo "yes isatty 1"
				else
					echo "no isatty 1"
				end
			end

		result:
			writes to terminal:
				yes isatty 1

	- eg1.2
		fish code:
			begin
				if isatty 1
					echo "yes isatty 1"
				else
					echo "no isatty 1"
				end
			end > tempfile.txt

		result:
			writes to file:
				no isatty 1

--
	- eg2.1
		fish code:
			begin
				echo "line 1"
				echo "line 2"
				echo "line 3"
			end > tempfile.txt

		result:
			the file contains:
				line 1
				line 2
				line 3


	- eg2.2
		fish code:
			begin
				echo "line 1"
				echo "line 2" > /dev/stdout
				echo "line 3"
			end > tempfile.txt

		result:
			to the terminal gets written:
				line 2

			and the file contains:
				line 1
				line 3

--
	- eg3.1
		fish code:
			begin
				ls
			end > tempfile.txt

		result:
			this was run in a dir containing two files:
				f1
				f2
			the file tempfile.txt ended up containing:
				f1
				f2
				tempfile.txt


	- eg3.2
		fish code:
			begin
				ls > /dev/stdout
			end > tempfile.txt

		result:
			again, run in a dir containing two files:
				f1
				f2

			it wrote to the terminal:
				f1  f2  tempfile.txt

			and the file tempfile.txt ended up being empty


--
	- eg4.1
		fish code:
				if isatty 0
					echo yup
				else
					echo no
				end

		result:
			writes to terminal:
				yup

	- eg4.2
		fish code:
				if isatty 0
					echo yup
				else
					echo no
				end < tempfile.txt

		result:
			writes to terminal:
				no