Hi. I hope this is a appropriate place to ask this question, because it feels like a matlab question. So, I have the following piece of code,

clear;
load('metadata.mat');                                                            
seqF = fastaread('nCoV_align_trim_0310.fas');                                    
                                                         % seqF is a struct with two fields, i.e., Header and Sequence
seqMetadata = [];                                        

for i = 1:length(seqF)                                                  
    seqF(i).Header = erase(seqF(i).Header,'_');                         
    seqF(i).Header = erase(seqF(i).Header,' ');                         
    found = false;                                                      
    for j = 1:length(allMetadata)                                       
        md = allMetadata(j);                                            
        mdName = md.id;                                                 
        if strcmp(mdName(1:9),' BetaCoV/')                               
            mdName = mdName(10:end);
        end
        if strcmp(seqF(i).Header,mdName)                           
            found = true;
            break;
        end
    end
    if found
        seqMetadata = [seqMetadata md];
    end
end

I was confused about the second for loop. I mean, what exactly is this allMetadata variable ? It looks like it is not defined anywhere else, right? Any comments are greatly appreciated.