%lettersPattern Creates a pattern that matches letter characters
%   PAT = lettersPattern returns a pattern that matches one or more
%   letters.
%
%   PAT = lettersPattern(N) returns a pattern that matches exactly N letters.
%
%   PAT = lettersPattern(minLetters,maxLetters) returns a pattern that matches 
%   at least minLetters letters and no more than maxLetters letters.
%
%   Examples
%       STR = "Four score and seven years ago";
%
%       PAT = lettersPattern;
%       extract(STR,PAT)         % returns ["Four";"score";"and";"seven";"years";"ago"]
%
%       PAT = lettersPattern(3);         
%       extract(STR,PAT)         % returns ["and"; "ago"]
%
%       PAT = lettersPattern(2,4);         
%       extract(STR,PAT)         % returns ["Four";"and";"ago"]
%
%   See also pattern, digitsPattern, alphanumericsPattern, contains, extract.

%   Copyright 2019-2020 The MathWorks, Inc.