Write the code for the following function:

def possibleFollowingStates$($initialState: List$[$List$[$char$]])->$ List$[$List$[$List$[$char$]]]$

where the input initialState consists of a list of lists of chars representing a matrix of board pieces in the game Huarong Pass. These chars include $".","<",">","$v$","^","1","2"."."$ represents an empty space which pieces can move into, $"<"$ and $">"$ represent the left and right sides of a $2$ by $1$ horizontal block, $"^"$ and $"$v$"$ represent the top and bottom of a $1$ by $2$ verticle block, $"1"$ represents a section of a $2$ by $2$ square block $(4$ sections total touching one another$),$ and $"2"$ represents a single $1$ by $1$ block. The goal is given some initial state the function returns all possible subsequenct states that can be derived for a board of width $4$ by length y where y can be any positive number. See below for an example of an initial state and a single subsequent state.

$2^22$

$2$v$<>$

$<><>$

$11.^$

$11.$v

$2^22$

$2$v$<>$

$<><>$

$\mathrm{.}11^$

$\mathrm{.}11$v