Resolve "Create function reed_decode"

Closes #16

See merge request !15

# Conflicts:
#   reed_solomon.py

Resolve "Create Lagrange method"

Closes #12

See merge request !10

# Conflicts:
#   reed_solomon.py

Resolve "Create function get_possibilities"

Closes #11

See merge request !11

# Conflicts:
#   reed_solomon.py

Resolve "Create check number error"

Closes #13

See merge request !12

Resolve "Fix the show method"

Closes #14

See merge request !13

Resolve "Remake Modular inverse"

Closes #10

See merge request !9