[Python] What are variables generated as "_1", "_2", "_3"... "_1i"...."_" when printing dir()?

I am running Python with IPython. Out of nowhere the following variables are being created when I print dir().

Here are some of the variables with following code:

for i in dir():
if "_" in i:
print(i)

# Output:
_
_12
_13
_14
_15
_19
__
___

_i
_i1
_i10
_i11
_i2
_i3
_i4
_i5
_i6
_i7
_i8
_i9
_ih
_ii
_iii
_oh

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