"""

Mark a point in a long text by line no + column with context lines around.

"""

assert isinstance(text, str)

assert line_no >= 0

assert column >= 0

assert extra_lines >= 0

lines = text.splitlines()

line_count = len(lines)

assert line_no <= line_count

from_line = line_no - extra_lines - 1

if from_line < 0:

from_line = 0

to_line = line_no + extra_lines

if to_line > line_count:

to_line = line_count

line_no_width = len(str(from_line)) + 1

lines = lines[from_line: to_line]

result = []

for no, line in enumerate(lines, from_line + 1):

result.append(

f'{no:0{line_no_width}} {line}'

)

if no == line_no:

result.append(

f'{"-"*(line_no_width+column+1)}^'

)