function m = addZero2One(m, to, fwd)
% ADDZERO2ONE adds a reaction 0 -> x(1) to the model
%
% m = addZero2One(m, to, fwd) addes a reaction of the form:
%
%    p(fwd)
% 0 -------> x(to)
%
% 
% See also
%   addProdDeg
%   addOne2One
%   addOne2Zero

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% Works 3.0 United States License. To view a copy of this license, visit 
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    m = kadd(m, to, fwd, 1);
    
    % add term to stoichiometry matrix    
    m.nR = m.nR + 1;
    [m.spinds.i_S, m.spinds.j_S, m.spinds.x_S, m.spinds.n_S] = ...
            sparse_vec(m.spinds.i_S, m.spinds.j_S, m.spinds.x_S, m.spinds.n_S, to, m.nR, 1);
end