Python3

arrayname[::-1]  # reverse, backwards

zip(*ARRAY)  # transpose array

dir(object)  # see all attributes

[ (do x) for x in array if x==whatever]

lambda a,b: a+b

df = pd.Dataframe(data, index=, columns=)
df.sort_values('', ascending=ToF)
pd.concat(df1, df2)
df.rename(columns = {'x': 'y'})
df.drop(columns=['',''])


### loop through files and build 1 df
if isinstance(df, pd.DataFrame):
    df = pd.concat([df, nextin], ignore_index=True)
else:
    df = nextin


### print n idxs around idx that satisfys condition
idx = df.index.get_indexer_for(condition.index)
print(idx) # array of ids that fit the condition above
n = 2
input(df.iloc[np.unique(
    np.concatenate(
        [np.arange(max(i-n,0), min(i+n+1, len(df))) for i in idx]))])


(df['v'].shift() != df['v']).cumsum() #split continuous same


df['max_fwd'] = df.price.rolling(window=daysf).max().shift(1 - daysf)

### quick test
print(df.info())
print(df.iloc[:, [columnsints]])

a = TestClass(1000)

a.instance_mthd(2)
# Instance method, with 'self': 2000

TestClass.class_mthd(2)
# Class method, with `cls`: 400

a.static_mthd(2)
# Static method, with neither args: 2

which pip
pip show $PACKAGE
pip install $PACKAGE --user 
pip list

open
print
compile
eval
exec
input
repr

bytearray
bytes

vars
dir
format

isinstance
callable
issubclass

zip
tuple  # immutable seq objtype
map
sorted
list
filter
frozenset
set
iter
reversed
slice

len
range
enumerate
breakpoint
hash
id
next

object
bin
oct
hex
int
chr
str
ord
ascii
bool
float
complex
dict

divmod
max
min
pow
round

all
any

@property
getattr
hasattr
delattr
type

@staticmethod
@classmethod
super
globals
locals
help

hashlib
concurrent.futures
argparse
functools
numba
asyncio